GE Multilin
T60 Transformer Protection System
5-215
5 SETTINGS
5.6 GROUPED ELEMENTS
5
Figure 5–98: PERCENT DIFFERENTIAL CALCULATIONS
The T60 percent differential element is based on a configurable dual-breakpoint / dual-slope differential restraint character-
istic. The purpose of the preset characteristic is to define the differential restraint ratio for the transformer winding currents
at different loading conditions and distinguish between external and internal faults. Differential restraint ratio variations
occur due to current unbalance between primary and secondary windings and can be caused by the following:
1.
Inherent CT inaccuracies
2.
Onload tap changer operation: it adjusts the transformer ratio and consequently the winding currents
3.
CT saturation
...
∑
Winding 1
current
waveform
Winding 2
current
waveform
Winding ‘n’
current
waveform
Magnitude
phase angle, and
zero sequence
compensation
(as required)
Magnitude
phase angle, and
zero sequence
compensation
(as required)
Magnitude
phase angle, and
zero sequence
compensation
(as required)
Decaying dc
offset filter
Decaying dc
offset filter
Decaying dc
offset filter
Discrete Fourier
Transform
MAX
Differential
phasor
Discrete Fourier
Transform
Discrete Fourier
Transform
Restraint
phasor
828714A1.CDR
Summary of Contents for T60
Page 6: ...vi T60 Transformer Protection System GE Multilin TABLE OF CONTENTS ...
Page 14: ...xiv T60 Transformer Protection System GE Multilin TABLE OF CONTENTS ...
Page 34: ...1 20 T60 Transformer Protection System GE Multilin 1 5 USING THE RELAY 1 GETTING STARTED 1 ...
Page 490: ...5 344 T60 Transformer Protection System GE Multilin 5 10 TESTING 5 SETTINGS 5 ...
Page 522: ...6 32 T60 Transformer Protection System GE Multilin 6 5 PRODUCT INFORMATION 6 ACTUAL VALUES 6 ...
Page 536: ...7 14 T60 Transformer Protection System GE Multilin 7 1 COMMANDS 7 COMMANDS AND TARGETS 7 ...
Page 568: ...10 12 T60 Transformer Protection System GE Multilin 10 6 DISPOSAL 10 MAINTENANCE 10 ...
Page 596: ...A 28 T60 Transformer Protection System GE Multilin A 1 PARAMETER LISTS APPENDIX A A ...
Page 716: ...B 120 T60 Transformer Protection System GE Multilin B 4 MEMORY MAPPING APPENDIX B B ...
Page 762: ...E 10 T60 Transformer Protection System GE Multilin E 1 IEC 60870 5 104 PROTOCOL APPENDIX E E ...
Page 774: ...F 12 T60 Transformer Protection System GE Multilin F 2 DNP POINT LISTS APPENDIX F F ...